Process for the preparation of polymers of cyclopentene or copolymers of cyclopentene with unsaturated alicyclic compounds

ABSTRACT

There is disclosed a process for the preparation of polymers of cyclopentene or copolymers of cyclopentene with non-conjugated unsaturated alicyclic compounds containing at least 7 carbon atoms in the ring and at least one double bond in the ring or polycyclic olefins or non-conjugated diolefins by the use of the catalyst system comprising (a) tungsten halides or oxyhalides, (b) an organoaluminum compound, (c) an alcohol, and (d) a halogenated phenol.

This invention is directed to a process for the ring-openingpolymerizaton of unsaturated alicyclic hydrocarbons. It is also directedto novel catalyst systems useful for this ring-opening polymerizationprocess. These catalyst systems are further useful for theinterconversion of acyclic olefins according to the method known as theolefin metathesis reaction (also called the olefin dismutation or olefindisproportionation reaction).

The olefin metathesis reaction is a unique bond reorganization process,whereby materials possessing carbon-to-carbon double bonds undergo aredistribution of constituents as depicted by the example in thefollowing equation: ##STR1##

This novel reaction is known to proceed by the cleavage of thecarbon-to-carbon double bond in the reacting ofefin. The reaction can bevisualized as a random recombination of these halves of olefins, oralkylidene moieties, to give all the possible combinations allowed fromthe starting material or mixture of materials chosen.

The olefin metathesis reaction, being an equilibrium process,facilitates: (1) obtaining the olefins R¹ CH═CHR¹ and R² CH═CHR²starting from R¹ CH═CHR² ; or alternatively, (2) obtaining the olefin R¹CH═CHR² by starting from a mixture of olefins R¹ CH═CHR¹ and R² CH═CHR².

Similarly, the ring-opening polymerization reaction of cycloolefins alsoinvolves the scission of the carbon-to-carbon double bonds in thecycloolefin ring. The alkylidene carbons are rejoined to other suchcarbons derived from other monomer units to form the linear unsaturatedpolymer chain. Thus, the ring-opening of cyclopentene, for instance,yields a repeat unit:

    ═CH--CH.sub.2 --CH.sub.2 --CH.sub.2 --CH═

In describing polymers which have been obtained from cyclopentene, thisrepeat unit has also been expressed in the following equivalent forms:

    --CH═CH--CH.sub.2 --CH.sub.2 --CH.sub.2 --, and

    --CH.sub.2 --CH═CH--CH.sub.2 --CH.sub.2 --

processes for the metathesis polymerization of cycloolefins are known inthe art. These procedures teach the use of a variety of transition metalcompounds in combinations with various cocatalysts and catalystmodifiers for the ring-opening polymerization or copolymerization ofcycloolefins. Exemplary of such processes is the use of oxygenatedcatalyst modifiers bearing oxygen-oxygen or oxygen-hydrogen bonds, incombinations with salts of tungsten or molybdenum and additionally anorganometallic compound, as taught in U.S. Pat. No. 3,449,310. Theprocess of this teaching has been shown to be effective for thepolymerization of cyclopentene in the absence of solvents, but inferiorresults are obtained when diluents are employed. Relatively highcatalyst levels are then required, preferably a transition metal/monomerratio of 1/2000 or greater, and rates of polymerization are low.

It has been further taught in the art that, with appropriate choice ofcatalyst modifiers, good rates of polymerization can be obtained even inthe presence of diluents, and solution polymerization techniqueseffective for industrial application may be employed. Exemplary of suchprocesses is the use of various phenols containing 1-4 halogen atomssubstituted on the aromatic ring as modifiers for tungsten salts incombination with organoaluminium compounds as catalysts for cyclopentenepolymerizations, described in U.S. Pat. No. 3,631,010. This process issuitable for use in aromatic solvents, but markedly inferior results arefrequently obtained when aliphatic solvents are employed; particularlyif only one halogen atom is present on the phenolic ring. Furthermore,prior art dealing with the preparation of cyclopentene polymers andcopolymers abounds with examples of the use of aromatic or halogenatedsolvents, but significantly, there is a paucity of examples whereinaliphatic or cycloaliphatic solvents have been used, because oftechnical difficulties encountered relating to low catalyst activity inthe use of these solvents.

An object of this invention therefore is to provide methods wherebyuseful polymers and copolymers of cyclopentene can be prepared inaliphatic or cycloaliphatic solvents rather than aromatic solvents.Industrial processes in these cases would benefit because of the greaterease in handling of the less viscous polymer solutions which result, andthe greater ease of polymer recovery made possible through the use ofmore volatile, lower-boiling aliphatic or cycloaliphatic solvents thanare available in the case of aromatic solvents.

More specifically, the novelty of the present invention relates to theuse of polyhalophenols (D) of the general formula: ##STR2## where X andY are chlorine or bromine, Q, L and M are selected from the groupconsisting of H, Cl, Br and R, wherein R is C_(n) H_(2n+1) and n is 1 to4, and wherein at least one of Q, L and M is H or R, as polymerizationcatalyst modifiers.

It has been discovered that, if the phenol does not contain halogens inboth positions adjacent to the --OH substituents (i.e., positions 2 and6), markedly inferior results are unexpectedly obtained whenpolymerizations are conducted in aliphatic solvents.

The required polyhalophenols of the present invention can be used toproduce catalyst systems which exhibit excellent activity ascyclopentene ring-opening polymerization catalysts. These catalystsystems exhibit high rates of polymerization, they yield hightrans-vinylene polymers of practical value, and they exhibit goodtolerance for diene and olefin impurities in the monomer. Furthermore,very low catalyst concentrations may be used with excellent results. Andof unique and practical significance, it has been discovered that thesecatalyst systems retain their advantages when aliphatic polymerizationsolvents are used. Thus, good yields of product can be obtained when themolar ratio of transition metal:monomer is as low as 1:10,000 or lesseven when aliphatic solvents are employed.

The process of this invention comprises the ring-opening polymerizationor copolymerization of cyclopentene with at least one unsaturatedalicyclic compound selected from the group consisting of (1)non-conjugated, unsaturated alicyclic compounds containing at leastseven carbon atoms in the ring and at least one double bond in the ring,and (2) polycyclic olefins and polycyclic, non-conjugated diolefins, bysubjecting said alicyclic compounds or their mixtures to polymerizationconditions in the presence of a catalyst system comprising (A) atransition metal salt selected from the group consisting of tungstenhalides and oxyhalides, (B) an organoaluminum compound, (C) at least onehydroxy compound of the general formula ROH wherein R is selected fromthe group consisting of alkyl, cyanoalkyl, cycloalkyl, aralkyl,alkoxyalkyl and aryl, and (D) a polyhalophenol of the general formula:##STR3## where X and Y are chlorine or bromine, Q, L and M are selectedfrom the group consisting of H, Cl, Br and R, wherein R is C_(n)H_(2n+1) and n is 1 to 4, and wherein at least one of Q, L and M is H orR and wherein the molar ratio of A:B:C:D lies within the range of1:0.5-10:0.5-3:0.1-3.

The molar relationship of the various catalyst components may also beexpressed as A/B ranging from 1/0.5 to 1/10, A/C ranging from 1/0.5 to1/3.0 and A/D ranging from 1/0.1 to 1/3.0. Also, the transition metal issometimes referred to as W, the organoaluminum compound as Al, thehydroxy compound as ROH, and the polyhalophenol as PHP.

The polymerization catalysts of this invention may be employed toprepare a wide variety of useful polymers having different propertiesdepending upon the particular combination of monomers chosen to bepolymerized, the particular catalyst combination employed and theparticular polymerization conditions employed. The linear, unsaturatedproducts resulting from the use of the polymerization catalysts of thisinvention can be employed in a variety of applications. For example,they may be employed to produce finished rubber articles such aspneumatic tires, molded goods and the like, or these materials may beuseful in coatings, in adhesives, or in the manufacture of articles suchas films and fibers.

Representative but not restrictive of the unsaturated alicyclic monomersdescribed in (1) above are cycloheptene, cyclooctene, cyclodecene,cyclododecene, 1,5-cyclooctadiene, 1,9-cyclohexadecadiene,1,5,9-cyclododecatriene, 3-methylcyclooctene, 3-phenylcyclooctene,1-methyl-1,5-cyclooctadiene, 1-chloro-1,5-cyclooctadiene,1,2-dimethyl-1,5-cyclooctadiene, and the like.

Representative of the transition metal salts of (A) are tungstenhexachloride, tungsten hexabromide, tungsten oxytetrachloride, tungstenoxytetrabromide, tungsten hexafluoride and the like. However, it ispreferred to use tungsten hexachloride or tungsten oxytetrachloride.

Representative of the organoaluminum catalyst components in (B) aboveare trimethylaluminum, triethylaluminum, triisobutylaluminum,diethylaluminum chloride, diisobutylaluminum chloride, diethylaluminumfluoride, dipropylaluminum bromide, ethylaluminum sesquichloride,methylaluminum sesquibromide, butylaluminum sesquichloride,ethylaluminum dichloride, propylaluminum dichloride, isobutylaluminumdibromide and the like. Of these, it is usually preferred to employorganoaluminum chlorides or trialkylaluminum compounds.

Representative but not restrictive of the ROH compounds useful as the(C) catalyst component of the present invention are the simple aliphaticalcohols such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyland t-butyl alcohol, cyclopentanol, cyclohexanol, phenol, alkyl phenolssuch as o- m- and p-cresol and the like, and substituted alcohols suchas benzyl alcohol, 2-cyanoethanol, 2-ethoxyethanol, 2-methoxyethanol,and the like.

Compounds useful as the (D) catalyst component of the present inventionare 2,6-dichlorophenol, 2,6-dibromophenol, 2-bromo-6-chlorophenol,2,6-dichloro-4-methylphenol, 2,6-dichloro-3,4,5-trimethylphenol,2,6-dibromo-3-butylphenol, 2-bromo-4-ethyl-6-chlorophenol,2,4,6-trichlorophenol, 2,4,6-tribromophenol, 2,3,4,6-tetrachlorophenol,4-methyl-2,3,5,6-tetrachlorophenol, 2,3,6-tribromophenol,2,3,6-trichlorophenol and the like. Of these, 2,6-dichlorophenol,2,6-dibromophenol, 2,4,6-trichlorophenol and 2,4,6-tribromophenol arepreferred.

The polyhalophenols of this invention may be used in combinations withthe (A) and (B) compounds in the absence of the (C) catalyst component,and significant rates of polymerization can be obtained. However, it ispreferred to employ the (C) components in combinations with thepentahalophenol.

The catalyst systems set forth above are prepared by mixing thecomponents by known techniques. Thus, the catalyst systems may beprepared by "preformed" or "in situ" techniques, or by a combination ofthese techniques. By the preformed method, the catalyst components aremixed together prior to exposure to any of these components to thealicyclic monomers to be polymerized. In the "in situ" method, thecatalyst components are added individually to the alicyclic monomers. Inthe handling and transfer of the catalyst components, it is oftenconvenient to utilize solutions of these components in suitable inertsolvents such as benzene, toluene, chlorobenzene, hexane, cyclohexane,pentane, cyclopentane and the like.

The order of addition of the catalyst components to each other is ofinterest in the practice of this invention.

When the in situ method is employed solely, it is much preferred to addthe B component last, but the particular order of addition of the A, Cand D components is generally not critical. Combinations of in situ andpreformed methods can also be used effectively. In this case, it isgenerally preferred to employ the B component according to the in situmethod, but component A may be preformed with component C or D or withboth C and D. However, if either the C or the D component is to be usedaccording to the in situ method, then it is preferred that the Bcomponent be the last one to be added to the monomer or mixture ofmonomer.

It has been found that when the preformed technique is employed with thecatalyst components A, C and D, some aging of the mixture of thecomponents is desirable. During this aging period, color changes areusually observed. This aging period may require only a few minutes, orit may take several hours. The aging process can be carried out atambient temperature in the range of 20° C.-25° C., or it may beaccelerated by the use of moderately elevated temperatures in the rangeof 30° C.-100° C.

It has also been found to be advantageous to remove some of the hydrogenchloride which is formed as a by-product when the preformed method isused. Known techniques may be used for removal of this hydrogenchloride. These techniques include the use of a stream of an inert gaswhich can be bubbled through the catalyst solution, or the use of avacuum, to withdraw vapors of hydrogen chloride.

The amount of catalyst employed in the practice of this invention mayrange over a wide concentration range. Of course, a catalytic amount ofthe catalyst must be employed but the optimum amount depends upon anumber of factors such as the temperature employed, the particularalicyclic monomers employed, the purity of the reaction conditionsemployed, the reaction time desired and the like. Generally, it ispreferred to use at least about 1 mole of the A component per 20,000moles of total monomer or mixture of monomers.

The operating conditions which are employed in the process of thisinvention may vary. The polymerization may be carried out in solution orin bulk. When solvents or diluents are employed, they should be chosenso as not to adversely affect the desired polymerization process.Representative examples of useful solvents are liquid aromatichydrocarbons such as benzene, toluene and chlorobenzene, aliphaticsaturated hydrocarbons such as pentane, hexane, heptane, petroleum etherand decane, and alicyclic saturated hydrocarbons such as cyclopentane,cyclohexane, decalin and the like.

The temperature at which the polymerization can be carried out can bevaried over a wide range. It is generally preferred to conduct thesepolymerizations under relatively mild reaction conditions over the rangeof about -50° C. to about 100° C.

The polymerization times will vary and can range from less than a minuteto 24 hours or more depending upon the polymerization conditions and theextent of polymerization desired. Generally, however, a satisfactorypolymerization product is obtained in a matter of only a few minutes orhours.

The polymerization reaction may be carried out as a batch or as acontinuous process. In performing the polymerization of this invention,the introduction of the monomer, catalyst and solvent--when a solvent isemployed--can each be made to the reaction zone intermittently and/orcontinuously. When copolymerizations are to be carried out, it may beparticularly advantageous to employ a continuous polymerization process.

The practice of this invention is further illustrated by reference tothe following examples, which are intended to be representative ratherthan restrictive of the scope of this invention. All experiments wereconducted in an atmosphere of dry nitrogen.

EXAMPLES 1-60

This series of experiments illustrates the uniqueness of phenolscontaining halogens in both positions adjacent to the phenolic OH-groupas catalyst modifiers for cyclopentene polymerizations in an aliphaticsolvent. All manipulations during premix (monomer plus solvent) dryingand charging and catalyst addition were carried out under an atmosphereof dry nitrogen.

The "preformed" technique was used to prepare solutions of WCl₆ modifiedwith the various phenols designated in Table I, in combinations withethanol as a co-modifier. An equimolar amount of ethanol was first addedto an 0.05 molar solution of WCl₆ in dry toluene, then the appropriatephenolic modifier was added and the mixture was allowed to react forabout 2 hours at room temperature. The solution was then flushed withdry nitrogen to expel HCl. C₂ H₅ AlCl₂ (EADC) was employed as thecocatalyst, as a 0.20 molar solution in dry toluene.

Polymerizations were conducted using a premix solution containing 24% byweight of cyclopentene in hexane, which has been purified by beingpassed through a column containing a mixture of silica gel and alumina.Polymerizations were carried out using 40 ml of dried premix charged to4-oz. glass, screw-capped bottles. Catalyst solutions were introduced bysyringe. Polymerizations were carried out at 0° C., and were initiatedby addition of the tungsten component, followed by the EADC. The molarratio of cyclopentene/tungsten was about 6250/1 for these examples.

Polymerizations were terminated after 90 minutes with a small amount ofmethanol, and the resulting solutions were dried in entirety for yields.In experiments where no phenolic modifier was employed, yields were lessthan 1%. For all experiments in Table I, the products were rubberypolypentenamers resulting from ring-opening polymerization.

                                      TABLE I                                     __________________________________________________________________________    Percent Conversions of Cyclopentene to                                        Polypentenamer with Different                                                 Phenolic Catalyst Modifiers                                                   Example          Phenol/W.sup.a                                                                      1     2     3                                          Number                                                                               Phenol    A1/W.sup.b                                                                          2  3  3  4  3  4                                       __________________________________________________________________________    1-6  o-chlorophenol    3.9                                                                              3.8                                                                              0.7                                                                              7.5                                                                              0.0                                                                              3.7                                     7-12 p chlorophenol    1.9                                                                              4.7                                                                              2.0                                                                              1.8                                                                              0.0                                                                              2.0                                     13-16                                                                              2,4-dichlorophenol                                                                              1.9                                                                              3.3                                                                              3.7                                                                              3.1                                                                              0.0                                                                              1.6                                     19-24                                                                              3,4-dichlorophenol                                                                              1.9                                                                              2.2                                                                              0.0                                                                              1.7                                                                              0.0                                                                              0.4                                     25-30                                                                              2,6-dichlorophenol                                                                              34.4                                                                             7.9                                                                              51.7                                                                             62.4                                                                             7.2                                                                              36.5                                    31-36                                                                              2,4,5-trichlorophenol                                                                           4.8                                                                              2.5                                                                              2.3                                                                              10.4                                                                             0.0                                                                              0.5                                     37-42                                                                              3,4,5-trichlorophenol                                                                           0.0                                                                              3.2                                                                              1.3                                                                              2.2                                                                              0.0                                                                              0.0                                     43-48                                                                              2,4,6-trichlorophenol                                                                           45.3                                                                             53.7                                                                             54.4                                                                             57.5                                                                             4.0                                                                              0.0                                     49-54                                                                              2,3,4,5-tetrachlorophenol                                                                       0.0                                                                              4.3                                                                              3.8                                                                              5.3                                                                              0.0                                                                              4.5                                     55-60                                                                              2,3,5,6-tetrachlorophenol                                                                       15.6                                                                             53.9                                                                             71.8                                                                             66.0                                                                             73.4                                                                             73.3                                    __________________________________________________________________________     .sup.a Molar ratio of phenol to tungsten. Ethanol was employed in all         polymerizations at ethanol:WCl.sub.6 = 1:1 molar ratio.                       .sup.b Molar ratio of EADC:WCl.sub.6.                                    

The data in Table I illustrates rather markedly that the phenol used asa catalyst modifier must be substituted by a halogen in both positionsadjacent to the --OH; that is, the 2 and 6 positions, if such a phenolis to have good activity as a catalyst modifier.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:
 1. A process for the preparation of cyclopentene polymers and copolymers comprising the polymerization of cyclopentene or mixtures of cyclopentene and at least one nonconjugated, unsaturated alicyclic compound containing at least seven carbon atoms in the ring and at least one double bond in the ring, by subjecting cyclopentene or its mixtures with said nonconjugated unsaturated alicyclic compound to polymerization conditions in the presence of a catalyst system comprising (A) a transition metal salt selected from the group consisting of tungsten halides and tungsten oxyhalides, (B) an organoaluminum compound, (C) at least one hydroxy compound of the general formula ROH wherein R is selected from the group consisting of alkyl, cycloalkyl, alkoxyalkyl, aralkyl and aryl, and (D) a halogenated phenol of the general formula: ##STR4## where X and Y are chlorine or bromine and Q, L and M are selected from the group consisting of H and R, and where R=--C_(n) H_(2n+1) and n=1-4, and wherein at least one of Q, L and M is H or R, and wherein the molar ratio of A:B:C:D lies within the range of 1:0.5-10:0.5-3:0.1-3.
 2. A process according to claim 1 carried out at a temperature between -50° C. to +100° C., wherein an aliphatic or cycloaliphatic hydrocarbon or a mixture thereof, is employed as the polymerization solvent, and wherein the molar ratio of tungsten salt:total monomer is at least about 1:20,000. 